In known optical communications systems, optical/electrical interfaces are created at nodes. In known Wave Division Multiplexing (WDM) Systems modulated information carrying light beams of selected wavelengths transmitted on a common fiber, can be added/dropped while others are passed-through at each node using such interfaces.
The interfaces need to accommodate a variety of rates and data formats (transparency) and be remotely configurable. One such interface is an optical add/drop multiplexer. Such multiplexers find application in optical networks of the type disclosed in U.S. Pat. No. 6,301,254B1, Virtual Path Ring Protection Method and Apparatus. The '254 patent is assigned to the assignee hereof and is incorporated by reference.
Known multiplexers are often formed of discrete components which require numerous connections. They are expensive to fabricate and can present quality control and reliability issues. Many of these systems are not remotely configurable. Others utilize 3R regeneration (re-amplify, re-shape, re-time) which requires prior knowledge of the data format of the traffic, and, which results in loss of transparency.
There continues to be a need for more cost effective add/drop multiplexers which also exhibit improved reliability. Preferably such multiplexers could be used in a variety of network configurations. It would also be preferable if bit-rate transparency could be maintained in the optical paths.